This invention relates to medical, neurological leads of the type used for insertion into the human body, for transmission of therapeutic drugs and/or electrical signals to body organs such as the spinal cord or brain, for acute and chronic pain relief, acute and chronic treatment of disease, and the like. More specifically, this invention relates to the mechanisms and methods by which such leads are secured to the human body.
The field of the application of therapeutic drugs and electrical signals to bodily organs such as the spinal cord and brain is rapidly advancing. The assignee of the present invention, Medtronic, Inc. is a leader in the field. Scientists and engineers at Medtronic have created programmable, electronic, implantable devices which deliver drugs and/or electrical stimulation in programs of therapy for the benefit of mankind. Implantable electrical devices are now capable of relieving chronic, inoperable pain by interfering with the transmission of pain signals in the spinal cord and brain. Implantable drug delivery devices are capable of delivering pain relieving drugs to the same dramatic effect. Both types of devices are also capable of new therapies for treatment of a variety of diseases. An advantage of the electrical devices is that typically no drugs are necessary. With the drug delivery devices, an advantage is that drug dosages are reduced relative to other therapies because the drugs are delivered directly to desired locations of therapy, rather than in remote locations such as the blood vessels of the extremities, and without concern for bodily elimination or chemical interaction. New applications of electrical and drug delivery therapies to diseases and acute and chronic conditions are being discovered rapidly.
With the electrical devices, electrical stimulation is typically delivered from the devices to the body through wired leads, to electrodes. The electrodes are located on and exposed to the body on the distal extremity of the leads, and the leads typically extend into and along the epidural space of the spinal cord, or into the brain at surgically drilled boreholes. The leads may also be subcutaneous where necessary. As an example, leads may extend from devices implanted above the clavicles, under the skin, to a bore hole atop the skull, and thence deep into brain tissue. With the drug delivery devices, catheters, which for purposes of this description are also considered "leads," extend in similar ways. To date, as known to the inventor, leads in the described applications are typically smooth walled, plastic, tubular members, although variation is possible.
When surgery for implantation of neurological leads occurs and is completed, the human body reacts acutely in that soft tissues adjacent surgical openings close about the leads. Chronically, a fibrotic sheath develops. With smooth walled leads, neither the closed soft tissues nor the fibrotic sheaths are adherent to leads. As a consequence, neurological leads must generally be fixed to the body by sutures, or alternative anchors fastened to the leads and the human body.
U.S. Pat. No. 5,058,584, which illustrates an implantable electrical pulse or signal generator delivering bursts of high frequency stimulation to the epidural space of the spinal cord, is incorporated by reference.